U.S. patent number 4,089,848 [Application Number 05/654,163] was granted by the patent office on 1978-05-16 for extraction of protein food values from oats.
This patent grant is currently assigned to Du Pont of Canada Limited. Invention is credited to Albert Bell, John Roger Brooke Boocock, Richard Walton Oughton.
United States Patent |
4,089,848 |
Bell , et al. |
May 16, 1978 |
Extraction of protein food values from oats
Abstract
A process for the extraction of food values from oats is
disclosed. Acid-soluble protein may be obtained by de-oiling
comminuted groats, treating the de-oiled groats with an aqueous
solution of pH 9.5-11.5, acidifying the alkaline solution after
separation of insoluble material to a pH of 1.8-3.2, preferably
2.2-2.8, and separating acid-soluble protein from the acidified
solution after separation of insoluble material. Each step in the
process is controlled so as to minimize denaturing of acid-soluble
protein. Techniques for separation of acid-soluble protein from the
acidified solution are disclosed. The separation of other protein
products, bran, flour and gum is also disclosed. The use of protein
products as emulsifying agents is disclosed.
Inventors: |
Bell; Albert (Elginburg,
CA), Boocock; John Roger Brooke (Kingston,
CA), Oughton; Richard Walton (Odessa, CA) |
Assignee: |
Du Pont of Canada Limited
(Montreal, CA)
|
Family
ID: |
9788914 |
Appl.
No.: |
05/654,163 |
Filed: |
February 2, 1976 |
Foreign Application Priority Data
Current U.S.
Class: |
530/372; 127/29;
127/32; 426/565; 426/601; 426/602; 426/615; 426/656; 536/102;
536/114 |
Current CPC
Class: |
A23J
1/12 (20130101) |
Current International
Class: |
A23J
1/00 (20060101); A23J 1/12 (20060101); A23J
001/00 (); A23J 001/12 (); C07G 007/00 () |
Field of
Search: |
;260/112R
;127/29,32 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Food Engineering Aug., 1973, pp. 100-102, Cluskey et al. .
Cereal Chemistry, vol. 50, No. 4, pp. 475-481 Cluskey et al. .
Cereal Chemistry, vol. 50, No. 4, pp. 481-488, Wu et al. .
Chem. Abstracts. vol. 82, 1975, 110458f, Wu et al..
|
Primary Examiner: Schain; Howard E.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A process for the separation of acid-soluble protein from oats
comprising the steps of:
a. comminuting dehulled oats,
b. extracting oil from the comminuted groats so obtained using an
organic solvent for the oil,
c. treating the de-oiled groats so obtained at least once with an
aqueous alkaline solution of pH 9.5-11.5 and separating the
insoluble material therefrom,
d. acidifying the alkaline solution so obtained to a pH of 1.8-3.2
and separating the acid-insoluble material therefrom, and
e. separating acid-soluble protein from the solution of
acid-soluble material, whereby an acid-soluble protein that is not
significantly denatured is obtained.
2. The process of claim 1 in which the step of separating
acid-soluble protein from the solution of acid-soluble material is
selected from the group consisting of (i) increasing the pH of the
solution of acid-soluble material to 4.2-4.8 and separating the
precipitate of acid-soluble protein so formed, and (ii) freeze
drying the solution of acid-soluble material.
3. The process of claim 2 in which, in step (b), the organic
solvent is selected from the group consisting of hexane,
cyclohexane, commercial heptane and aliphatic alcohols of 1 to 6
carbon atoms.
4. The process of claim 3 in which, in step (c), the alkaline
solution is a solution of an alkali selected from the group
consisting of alkali metal hydroxides, calcium hydroxide and
ammonium hydroxide.
5. The process of claim 4 in which, in step (d), the alkaline
solution is acidified with a solution of an acid selected from the
group consisting of phosphoric acid, hydrochloric acid, fumaric
acid and citric acid.
6. The process of claim 2 in which the step of separating
acid-soluble protein from the solution of acid-soluble material
comprises increasing the pH of the solution of acid-soluble
material to 4.2-4.8 and separating the precipitate of acid-soluble
protein so formed.
7. The process of claim 6 in which in step (b) the organic solvent
is selected from the group consisting of hexane, commercial
heptane, 2-propanol and 1-butanol, in step (c) the alkaline
solution is a solution of sodium or potassium hydroxide and in step
(d) the acid is phosphoric acid or hydrochloric acid.
8. The process of claim 7 in which the solvent is hexane and the
acid is phosphoric acid.
9. The process of claim 2 in which the step of separating
acid-soluble protein from the acid-soluble material comprises
freeze drying the solution of acid-soluble material.
10. The process of claim 9 in which in tep (b) the organic solvent
is selected from the group consisting of hexane, commercial
heptane, 2-propanol and 1-butanol, in step (c) the alkaline
solution is a solution of sodium or potassium hydroxide and in step
(d) the acid is phosphoric acid or hydrochloric acid.
11. The process of claim 10 in which the solvent is hexane and the
acid is phosphoric acid.
12. The process of claim 2 in which the de-oiled groats is
extracted twice with the alkaline solution.
13. The process of claim 2 in which the insoluble material obtained
in step (c) in treated for the separation of fractions comprised of
starch, of bran or of gum.
14. The process of claim 1 in which, in step (d), the pH is in the
range 2.2-2.8.
Description
The present invention relates to the extraction of food values from
oats and especially to a process for the separation of, in
particular, so-called "acid-soluble protein" from oats. The process
is also capable of yielding other useful products. As used herein
the term "acid-soluble protein" refers to protein that is
substantially soluble in aqueous solutions of pH in the range about
2 to 3.
Products having a high protein content and capable of being used in
food may be obtained from a variety of sources, for example,
soybeans, cottonseed, wheat, corn, skim milk, white beans and
cheese whey. Techniques for the separation of protein from such
sources are known. For example, S. J. Circle and A. K. Smith
describe processes for the production of high-protein products from
soybeans in Chapter 9 of "Soybeans; Chemistry and Technology", AVI
Publishing Co. Inc., Westport, Conn., U.S.A., 1972. The production
of protein concentrates, starch and residue fractions from oats has
been described by J. E. Cluskey et al in Cereal Chemistry 50,
475-481 (1973). The properties of these protein concentrates,
starch and residue fractions were described by Y. V. Wu et al in
Cereal Chemistry 50, 481-488 (1973). The optimum yield of protein
was obtained using an alkali extraction at pH 8.9. After
centrifuging the resultant solution the pH of the solution was
adjusted to pH 6 and the protein product obtained was
freeze-dried.
The properties of the known products of high protein content
depend, in particular, on the source of the protein and on the
method of separation of the product from the source. Products
having properties suitable for some end uses are known but such use
of these products may not be economical. For other end uses no
suitable products are known.
It is desirable to be able to increase the nutritional value of
foods.
Potential end uses for products having high protein contents are in
foods, for example, some yogurts and especially beverages, that are
acidic, for example, beverages having a pH of less than 4.0. Such
beverages include a large number of the so-called soft drinks which
are sold throughout the world in very large quantities and the
beverages that are more commonly consumed during breakfast, for
example, organe juice and the like. If untreated protein products,
i.e., products that are not completely acid-soluble, are used in
acidic beverages, the beverage would likely contain a suspension of
insoluble matter which would have limited stability and tend to gel
or settle on standing. Protein products that are soluble in the
medium in which they are used are therefore desirable.
Acid-soluble protein may be obtained from cheese whey. However,
such protein may exhibit a cheese-like flavour when used at
concentrations of about 1% by weight, or higher, in acidic
beverages. Concentrations of 2- 3% acid-soluble protein may be
desired in acidic beverages. In addition, cheese whey is a valuable
food additive and it may not be an economic source of protein
products. Protein products obtained from soybeans usually require
hydrolysis to achieve acceptable solubility in acidic beverages.
For example, in U.S. Pat. No. 3,830,942 which issued Aug. 20, 1974,
R. L. Howley describes a process for the separation of an
acid-soluble protein product from soybeans. Such hydrolysis may
affect other useful properties of acid-soluble proteins including
the nutritional value of the product. Acid-soluble protein from
white beans and wheat tend to be low in nutritional value whereas
such protein products obtained from cottonseed require special
processing to ensure that the protein is free of toxic
components.
Oats are a potentially economic source of high protein products.
Such protein products may be acid-soluble or acid-insoluble.
Moreover, oats are a potentially economic source of oil, starch,
bran and gum, all of which are potentially useful in the food
industry. In addition oat hulls may be used as roughage in animal
feed or in the production of furfural. However, the known processes
for the extraction of oats have only yielded part, for example,
less than 60%, of the potentially available protein or have not
been adapted for recovery of other potentially useful products that
are obtainable from oats in a form suitable for uses other than the
feeding of animals.
It has now been found that by extraction of comminuted oats with
organic solvents and aqueous alkaline and acidic solutions it is
possible to obtain acid-soluble protein in high yield and in
addition to obtain other products of potential use in the food
industry.
Accordingly, the present invention provides a process for the
separation of acid-soluble protein from oats comprising the steps
of:
a. comminuting dehulled oats,
b. extracting oil from the comminuted groats so obtained using an
organic solvent for the oil,
c. treating the de-oiled groats so obtained at least once with an
aqueous alkaline solution of pH 9.5-11.5 and separating the
insoluble material therefrom,
d. acidifying the alkaline solution so obtained to pH of 1.8-3.2
and separating the acid-insoluble material therefrom, and
e. separating acid-soluble protein from the solution of
acid-soluble material,
and minimizing the denaturing of acid-soluble protein by carefully
controlling the reaction conditions in each of the above steps.
In a preferred embodiment of the process of the present invention
the step of separating acid-soluble protein from the solution of
acid-soluble material is selected from the group consisting of (i)
increasing the pH of the solution of acid-soluble material to
4.2-4.8 and separating the precipitate of acid-soluble protein so
formed, and (ii) freeze drying the solution of acid-soluble
material.
In another embodiment the organic solvent is hexane, cyclohexane or
an aliphatic alcohol of up to 6 carbon atoms, especially
2-propanol.
In yet another embodiment the acids used for acidification are
selected from the group consisting of phosphoric acid and
hydrochloric acid.
In still another embodiment the alkali used in the process is an
alkali metal hydroxide.
In a further embodiment the de-oiled groats are extracted twice
with the alkaline solution.
In a still further embodiment the insoluble material obtained in
step (c) is treated for the separation of starch, bran, gum and the
like therefrom.
The present invention also provides a process for the separation of
products from oats comprising the steps of:
i. comminuting dehulled oats,
ii. extracting oil from the comminuted groats so obtained using an
organic solvent for the oil,
iii. treating the de-oiled groats so obtained at least once with an
aqueous alkaline solution of pH 9.5-11.5 and separating the
insoluble material therefrom, and
iv. treating the insoluble material at least once with an aqueous
alkaline solution of higher pH than that of step (iii), said higher
pH being in the range 11.5-12.5, and separating the insoluble
material therefrom, and minimizing the denaturing of acid-soluble
protein by carefully controlling the reaction conditions in each of
steps (i), (ii) and (iii).
In an embodiment of this process of the invention the insoluble
material of step (iv) is treated for the separation of starch and
bran.
In another embodiment the liquid of step (iv) after separation of
the insoluble material is treated for the separation of gum.
In a further embodiment the liquid of step (iii) after separation
of the insoluble material is treated for the separation of
acid-soluble protein.
The process of the present invention is carried out on dehulled
oats. Techniques for dehulling oats are known in the art. The
dehulled oats are comminuted in order to facilitate extraction of
oil. Extraction of oil, and of protein, is facilitated by small
particle size of the comminuted oats, herein usually referred to as
comminuted groats. However, separation of solid material from
liquids in the process, e.g., the comminuted groats after
de-oiling, is facilitated by large particle size. Thus, the
particle size of the comminuted groats should be selected so as to
facilitate both the extraction of products from the comminuted
groats and the separation of solid material from liquids in the
process. The optimum size will depend at least in part on the
particular techniques used in the extraction steps and the
separation steps in the process. A particle size of about 20 mesh
(TYLER* Standard Screen Size) may be a suitable size.
The comminution of the dehulled oats may be accomplished by known
techniques, for example, by grinding or by rolling. In order to
obtain the desired particle size, it may be desirable to screen out
the particles of desired size on, for example, a continuous basis,
the groats particles that are oversized being recirculated to the
comminution step, or by using air classification techniques.
After comminution the comminuted groats so obtained is de-oiled. If
the comminuted groats are not de-oiled the oil may contaminate the
protein products subsequently obtained in the process and/or cause
other process problems. Such contamination may affect, in
particular, the stability of the protein products, e.g., rancidity
may occur. Moreover, the oil itself may be a commercially viable
product, for example, as a vegetable oil. The de-oiling of the
comminuted groats is accomplished with an organic solvent for the
oil. The organic solvent must be such that under the process
conditions the protein in the comminuted groats is not
significantly de-natured. The nature of the oil that is extracted
will depend at least in part on the particular organic solvent used
and on the other process conditions. Examples of solvents that may
be used to de-oil the comminuted groats are hexane, cyclohexane and
aliphatic alcohols of up to 6 carbon atoms, e.g., 1-butanol.
Preferred solvents are 2-propanol and hexane. The use of 2-propanol
is disclosed in the copending application of J. R. B. Boocock and
R. W. Oughton filed on the same day as the present application. The
solvent may be pure solvent or an azeotropic solvent/water mixture.
Techniques for the extraction of oil are known, for example, by
passing solvent through a bed of comminuted groats or by forming a
slurry of the comminuted groats and solvent. The oil, after
separation from the solvent, may be treated for sale, for example,
as a vegetable oil, or other use. The de-oiling may be carried out
at room temperature but elevated temperatures may also be possible.
De-oiling is continued until the oil content of the comminuted
groats is reduced to the desired level, for example, 0.2% by weight
of the groats. After de-oiling the de-oiled groats so obtained are
separated from the solvent.
The de-oiled groats are treated with an aqueous alkaline solution
of pH of about 9.5-11.5. Solutions of lower pH are inefficient for
the extraction of protein. Solutions of higher pH may denature the
protein. In this treatment in alkaline solution protein and some
other alkali-soluble materials, e.g., some of the gum, are
extracted from the de-oiled groats. Starch, fibrous matter and
other matter including some gum are insoluble in the alkaline
solution. Preferably, the pH of the alkaline solution is about 11.
The matter extracted from the de-oiled groats, and thus the
properties of the extracted matter, may depend on the particular
alkaline solution. Hydroxides of alkali metals, especially sodium
and potassium, ammonium hydroxide and calcium hydroxide are capable
of extracting protein from the de-oiled groats. Sodium and
potassium hydroxide are preferred. After the treatment with the
alkaline solution, insoluble material is separated from the
solution. The solid may be subjected to a further treatment with an
alkaline solution so as to extract more protein. Subsequently, the
remaining solid material is separated from the solution, this
solution being combined with the solution from the first alkaline
treatment. The alkali-insoluble material, which may be subjected to
further alkaline treatments, may subsequently be treated for
separation into its constituents. Such separation of the
alkali-insoluble material, which may be referred to herein as the
starch and bran fraction, is described hereinafter.
Techniques for liquid/solid separation are known. A typical example
involves the use of a centrifuge. The use of a centrifuge may be
the preferred technique especially if the particle size of the
solid matter is very fine.
The pH of the solution from the alkaline treatment is adjusted to a
pH of about 1.8-3.2, preferably 2.2-2.8, using an acid that does
not substantially denature the protein. Examples of suitable acids
are phosphoric acid and hydrochloric acid; sulphuric acid and
acetic acid would not appear to be suitable. Citric acid and
fumaric acid may be used but may be undesirable on economic
grounds. A fraction of the matter in the solution is insoluble at
such pH's and this insoluble fraction, which may be referred to
hereinafter as the conventional isolate, may be separated from the
acid soluble fraction. Known solid/liquid separation techniques,
especially the use of a centrifuge, may be used to separate the
conventional isolate from the solution. Conventional isolate may be
vendible as a protein food additive, as animal feed or as an
emulsifying agent.
The pH of the acid solution may be adjusted to 4.2 to 4.8 so as to
cause the precipitation of the so-called acid-soluble protein. The
optimum pH for isoelectric precipitation is believed to be about
4.5. Alkali metal hydroxides and ammonium hydroxide are suitable
for this adjustment of pH. The precipitated acid-soluble protein
may be separated from solution by known techniques, especially the
use of a centrifuge. The solution is believed to contain some
protein as well as gum, sugars and the like. The solution may be
recycled so as to separate the protein more efficiently. The other
materials in the solution are capable of being separated.
The acid-soluble protein is also separable from the acidic solution
at pH's of less than 4.2, e.g., by removal of water.
In a preferred embodiment the acid-soluble protein is obtained by
freeze drying a solution of acid-soluble protein of pH of about
1.8-3.2, preferably 2.2-2.8, as is exemplified hereinafter.
Alternatively, the acid-soluble protein may be useful without
separation from solution.
The wet acid-soluble protein may be dried by, for example, freeze
drying, vacuum drying or spray drying. The properties of the dried
acid-soluble protein may be dependent to some extent on the drying
technique used. The acid-soluble protein is capable of being used
in foods as an emulsifying agent and, in particular, in acidic
beverages. Acid-soluble protein may be used as an emulsifying agent
under acidic conditions, and hence is termed an acid-specific
emulsifying agent.
The starch and bran fraction may be treated with an alkaline
solution that is of higher pH, in the range 11.5-12.5, than that of
the alkaline solution used to treat the de-oiled groats. Preferably
the alkaline solution is of a pH of about 12. Alkali metal
hydroxides are the preferred basic materials for this solution. In
such a treatment the remaining gum and essentially all of the
remaining protein in the starch and bran fraction goes into
solution and the remaining solid material is comprised of starch
and a fibrous material. If the solids are separated from this
alkaline solution using centrifuging techniques the solids may be
partially separated into two fractions, a starch fraction and a
fibrous or "bran" fraction. Further separation may be effected by
using a 60 mesh (TYLER) screen, the fibrous or bran fraction being
retained on the screen. The material passing through the screen is
primarily starch. A protein-containing precipitate may be obtained
from the solution so obtained by adjusting the pH to 4.5 with say
phosphoric acid. After separation from the protein-containing
precipitate, the solution may be mixed with an aliphatic alcohol,
e.g., methanol, whereby a "gum" fraction is obtained as a
precipitate. This gum is believed to be of potential use in the
food industry where viscous materials are required, for example, as
a binder in ice cream. The bran may be used as animal feed. The
starch is believed to be vendible for end uses in which known
starch is used, e.g., the cosmetic, pulp and paper, and food
industries. The starch may also be hydrolyzed to sugars. The
protein-containing precipitate may be used as an emulsifying agent
as in exemplified hereinafter.
The products of the process of the present invention are capable of
being used as such in foodstuffs as is discussed herein. Matter
derived from the products of the process of the present invention
is also capable of being used in foodstuffs. Such matter may be
obtained by subjecting the products to further treatment by
physical means e.g. sieving, air classification, and/or by chemical
means e.g. by further extractions, separations and the like, as is
discussed herein and/or is known in the art.
The process of the present invention is illustrated by the
following examples:
EXAMPLE I
a. De-oiling of Groats
A dehulled oat, known as Hinoat and obtained from Agriculture
Canada, Ottawa, Ontario, was ground to -20 mesh (TYLER Standard
Screen Size). 240 g of the ground groats obtained was extracted
with 1800 ml of hexane for six hours on a modified Soxhlet
extraction apparatus. The modified Soxhlet apparatus permitted the
ground groats to be continuously extracted by fresh solvent
(hexane) at ambient temperature. After the six hours extraction had
been completed, the de-oiled groats obtained was first dried in air
and then under vacuum (63.5 cm Hg) to remove residual hexane. The
de-oiled groats were stored in a refrigerator at about 1.degree. C.
The amount of oil extracted was approximately 4.7%, by weight, of
the ground groats.
b. Extraction of Protein
About 20 g of the de-oiled groats were admixed, in the form of a
slurry, with 100 ml of distilled water and the pH of the slurry was
adjusted to 10.0 using a 1N sodium hydroxide solution. The slurry
was continuously agitated. Additional sodium hydroxide solution was
added periodically so as to maintain the pH at 10.0.
After one hour the slurry was centrifuged for 15 minutes using a
laboratory centrifuge. A good separation of solid material and
supernatant liquid was obtained at the 1500 G generated by the
centrifuge. The alkaline supernatant liquid was decanted from the
solid material. The solid material was then re-slurried with a
sodium hydroxide solution for a further hour using the above
procedure. Adjustment of the pH was required infrequently, if at
all. The slurry was centrifuged for 15 minutes and the alkaline
supernatant liquid decanted from the solids. These solids are
referred to in the Examples as "alkali-insoluble material".
The pH of the first alkaline supernatant liquid was adjusted to 2.6
using a 50% phosphoric acid solution. The solution was centrifuged
for 15 minutes and the acidic supernatant liquid decanted from the
solid material obtained. This solid material is referred to in the
Examples as "conventional isolate A". The pH of the acidic
supernatant liquid was adjusted to 4.5 using a 30% potassium
hydroxide solution to precipitate protein. The resultant solution
was centrifuged for 15 minutes and the supernatant liquid obtained
was discarded. The solid material is referred to in the Examples as
"acid-soluble protein A".
The second alkaline supernatant liquid was treated in the same
manner as the first alkaline supernatant liquid. The solid
materials obtained are referred to in the Examples as "conventional
isolate B" and "acid-soluble protein B" respectively.
The alkali-insoluble material was admixed, in the form of a slurry,
with 100 ml of water. The pH of the slurry was adjusted to 12 using
a 30% potassium hydroxide solution. After stirring continuously for
one hour the slurry was centrifuged for 15 minutes. The solid
material obtained is referred to in the Examples as the
"starch/bran fraction". The pH of the supernatant liquid was
adjusted to a pH of 4.5 in order to precipitate any protein. This
is referred to, in Example XV, as "insoluble protein". The solution
was centrifuged for 15 minutes. The supernatant liquid obtained was
mixed with 300 ml of methanol in order to precipitate a gum
fraction. The gum fraction, referred to in the examples as "gum",
was separated by centrifuging for 15 minutes.
All solid samples were dried by freeze-drying under vacuum.
The results reported hereinafter are based on the weight of ground
groats as follows ##EQU1## Thus, although the extraction of protein
was carried out on a weighed sample of de-oiled groats the results
are expressed as a percentage of the equivalent weight of the
ground groats. The ground groats contained approximately 9%
water.
The protein in the samples was determined using a Kjeldahl analysis
for nitrogen and multiplying the result obtained in per cent
nitrogen by the frequently accepted factor of 6.25 to give protein.
Acid-soluble proteins A and B were combined before the protein in
the acid-soluble protein was measured. The percentage of protein
recovered in the acid-soluble protein is defined as: ##EQU2## The
results are given in TABLE I as Run 1.
EXAMPLE II
To demonstrate the effect of varying the pH of the alkaline
solution, the procedure of Example I was repeated except that the
treatment with the alkaline solution waas carried out, in separate
runs, at pH's of 9, 11 and 12.
The results are given in TABLE I as Runs 2, 3 and 4.
EXAMPLE III
To demonstrate the effect of the acid used to adjust the pH of the
supernatant liquid, obtained on treatment with the alkaline
solution, from 10.0 to 2.6, the procedure of Example I was repeated
except that the phosphoric acid solution was replaced with
solutions of hydrochloric acid (Run 5), sulphuric acid (Run 6),
citric acid (Run 7), fumaric acid (Run 8) and acetic acid (Run 9).
These acids were used at concentrations similar to that of the
phosphoric acid of Example I.
The results of these runs are given in TABLE II.
EXAMPLE IV
To demonstrate the effect of the type of alkali used in the
alkaline treatment step, the procedure of Example I was repeated
except that the sodium hydroxide solution was replaced with
solutions of calcium hydroxide (Run 10), potassium hydroxide (Run
11) and ammonium hydroxide (Run 12).
The results of these runs are given in TABLE III.
EXAMPLE V
To demonstrate the effect of the solvent used in the de-oiling of
the ground groats, the procedure of Example I was repeated using
de-oiled groats that had been obtained by de-oiling ground groats
with methanol (Run 13), ethanol (Run 14), 2-propanol (Run 15),
1-propanol (Run 16) and t-butanol (Run 17).
The results of these runs are given in TABLE IV.
EXAMPLE VI
To demonstrate the effect of temperature of the solvent used in the
de-oiling of the ground groats, the procedure of Example I was
repeated except that the ground groats were de-oiled with hexane at
68.degree. C.
The results are given in TABLE V as Run 18.
EXAMPLE VII
In the procedure of Example I the oat was ground to -20 mesh.
Approximately 15% of such ground groats were capable of passing
through a 60 mesh screen. To demonstrate the effect of the particle
size of the ground groats the procedure of Example I was repeated
using oat that had been ground so that 50% would pass through a 60
mesh screen.
The results are given in TABLE V as Run 19.
EXAMPLE VIII
The procedure of Example I was repeated except that the de-oiled
groats were treated three times with an alkaline solution of sodium
hydroxide at pH 11.
The results are given in TABLE V as Run 20.
EXAMPLE IX
The procedure of Example I was repeated except that all volumes of
the liquids used in the "extraction" steps were increased by a
factor of two. The control of the pH of the solutions, where
applicable, resulted in small deviations from this factor for the
increase in volume.
The results are given in TABLE V as Run 21.
EXAMPLE X
To demonstrate the importance of the alkaline treatment step, the
procedure of Example I was repeated except that the alkaline
treatment step was omitted. The de-oiled groats were admixed, in
the form of a slurry, with 100 ml of water and the pH of the slurry
was adjusted to 2.6 with phosphoric acid. Two extractions were
carried out at pH 2.6. The pH of the supernatant liquid obtained on
centrifuging was adjusted to pH 4.5 and the acid-soluble protein
was separated as in Example I.
The results are given in TABLE VI as Run 22.
EXAMPLE XI
For comparative purposes an alternate procedure for the separation
of acid-soluble protein was tested. De-oiled groats were treated
with 100 ml of water at a pH of 7.0 for a period of one hour to
remove some of the gum. After centrifuging the remaining solid
material was treated once with a sodium hydroxide solution of pH
9.0 using the procedure of Example I. The resulting solution was
centrifuged and the pH of the supernatant liquid was adjusted to
5.0 with phosphoric acid. The precipitate obtained was separated
from the solution using a centrifuge and mixed with 100 ml of
water. The pH of the slurry obtained was then adjusted to 2.2 using
phosphoric acid. After stirring for 5 minutes the resulting
solution was centrifuged and the pH of the supernatant liquid was
adjusted to 7.0 using sodium hydroxide. The precipitate of
acid-soluble protein obtained was separated using a centrifuge.
The results are given in TABLE VI as Run 23.
EXAMPLE XII
1.0 g of the acid-soluble protein of Example I was admixed, in the
form of a slurry, with 100 ml of distilled water in a WARING*
blender for 15 seconds. The pH of the slurrry was then adjusted to
2.0 using phosphoric acid. The slurry was then returned to the
blender for a further 15 seconds. The resulting solution was
centrifuged and the protein content of the supernatant liquid was
determined by Kjeldahl analysis for nitrogen. 85.6% of the protein
in the acid-soluble protein was in the supernatant liquid.
When the procedure was repeated using a slurry of pH 3.0, 76.0% of
the protein was in the supernatant liquid.
EXAMPLE XIII
The starch-bran fraction of Run 18 was slurried with water and
sieved through a 60 mesh screen. 82.5% of the starch-bran fraction
passed through the screen. This fraction of small particle size is
believed to be mainly comprised of starch.
When the above procedure was repeated using the starch-bran
fraction of Run 20, 84.9% passed through the 60 mesh screen.
EXAMPLE XIV
The starch-bran fraction of Run 19 was sieved through a 60 mesh
screen while in a dry state. 85.7% of the starch-bran fraction
passed through the screen.
When the above procedure was repeated using the starch-bran
fraction of Run 15, 80.7% passed through the 60 mesh screen.
EXAMPLE XV
Approximately 1 part, by weight, of a protein product was stirred
with 99 parts of water having a desired pH until solution or
dispersion had been achieved. An equal volume of household
vegetable oil was added and the mixture was blended using a WARING
blender. The emulsion so formed was poured into a cylindrical glass
container and the height of the aqueous layer formed at the bottom
of the emulsion was measured periodically, the results being
expressed as a percentage of the total height of the emulsion
layer/water layer in the glass container.
The results are given in TABLE VII.
EXAMPLE XVI
40 grams of dehulled Hinoat oat that had been comminuted and
de-oiled were admixed with 200 ml of water in the form of a slurry.
The pH of the slurry was adjusted to 10.0 by the addition of a 1N
solution of sodium hydroxide. After one hour the slurry was
centrifuged for 15 minutes. The liquid was removed by decantation
and admixed with a solution of 50% phosphoric acid until the pH of
the resultant solution was 2.6. The solution was then centrifuged
to remove any solid material and freeze dried at ambient
temperature. 8.39 grams of a white material, a protein concentrate,
containing 68.1% protein (measured by macro Kjeldahl analysis) was
obtained. The protein concentrate was whiter than "acid-soluble
protein A", i.e., the solid material obtained by precipitation of
protein at a pH of 4.5 instead of by freeze drying (see Example I).
A taste test of a solution of pH 2.6 of the freeze-dried protein
concentrate indicated significantly less "mouthfeel" and sensation
of suspended particulate matter compared with that obtained in a
taste of a solution of pH 2.6 of acid soluble protein A.
In order to determine the solubility of the protein in the
freeze-dried protein concentrate, 0.8 g of protein concentrate were
admixed with 80 ml of distilled water in a WARING blender so as to
form a slurry. The pH of the slurry was adjusted to that desired by
the addition of either phosphoric acid or sodium hydroxide. After
15 minutes the resulting solution was centrifuged to remove any
remaining solid matter, decanted and analyzed for protein using
macro Kjeldahl analysis. The results were as follows:
______________________________________ pH of Solution Solubility of
Protein (%) ______________________________________ 1.99 100 3.24
100 3.93 92 5.19 19 5.99 19 6.94 19 8.02 19 9.06 28
______________________________________
TABLE I ______________________________________ Run Number 1 2 3 4**
______________________________________ Alkaline Treatment at pH 10
9 11 12 Conventional Isolate (wt.%) 0.6 0.7 0.9 -- (total of A and
B) Acid-soluble Protein (wt.%) A 15.5 10.3 14.5 -- B 1.6 3.4 3.2 --
Total 17.1 13.7 17.7 -- Starch-bran Fraction (wt.%) 56.2 54.9 61.0
-- Gum (wt.%) 0.6 0.7 3.3 -- Protein in Starch-bran Fraction (%)*
3.1 3.9 3.4 -- Protein in Acid-soluble Protein (%)* 91.9 91.3 86.3
-- Protein Recovered in Acid-soluble Protein (%) 74.9 57.5 66.2 --
______________________________________ *by Kjeldahl Analysis
**Separation of solid material and liquid after first alkaline
treatment was not achieved using a centrifuge.
TABLE II
__________________________________________________________________________
Run Number 5 6 7 8 9 Acid hydrochloric sulphuric citric fumaric
acetic
__________________________________________________________________________
Conventional Iso- late (wt. %) (total of A and B) 1.1 16.2 0.9 NA
0.7 Acid-soluble Protein (wt. %) A 14.9 2.1 18.3 11.6 20.6 B 1.7
0.0 1.8 1.1 2.5 Total 16.6 2.1 20.1** 12.7 23.1* Starch-bran
Fraction (wt. %) 53.5 46.6 57.4 56.8 55.6 Gum (wt. %) 1.0 0.9 0.9
1.2 0.6 Protein in Starch- bran Fraction (%) 3.4 3.2 3.3 3.5 2.8
Protein in Acid- Soluble Protein (%) 95.2 91.0 79.3 94.4 65.4
Protein Recovered in Acid-soluble Protein (%) 73.1 8.6 76.1 57.8
72.1
__________________________________________________________________________
*protein was badly discoloured. **product contained citric acid. NA
not available
TABLE III ______________________________________ Run Number 10 11
12 calcium potassium ammonium Alkali hydroxide hydroxide hydroxide
______________________________________ Conventional Isolate (wt. %)
(total of A and B) 1.5 1.8 2.1 Acid-soluble (wt.%) A 15.6 16.6 13.7
B 5.4 1.1 2.1 Total 21.0* 17.7 15.8 Starch-bran Fraction (wt. %)
60.2 54.8 55.7 Gum (wt. %) 1.7 1.3 2.1 Protein in Starch-bran
Fraction (%) 3.6 2.4 2.8 Protein in Acid-soluble Protein (%) 47.1
87.4 88.3 Protein Recovered in Acid-soluble Protein (%) 49.3 77.4
69.7 ______________________________________ *product contained
calcium hydroxide
TABLE IV ______________________________________ Run Number 13 14 15
16 17 meth- eth- 2-pro- 1-pro- t-but- De-oiling Solvent anol anol
panol panol anol ______________________________________ Oil
Separated from Ground Groats (wt.%) 4.52 4.45 5.93 5.22 3.58
Conventional Isolate (wt. %) (total of A and B) 0.7 0.4 1.2 0.7 0.5
Acid-soluble Protein (wt. %) A 17.4 16.7 15.3 14.6 15.9 B 2.0 1.2
2.1 1.9 1.4 Total 19.4 17.9 17.4 16.5 17.3 Starch-bran Fraction
(wt. %) 56.5 56.9 57.3 57.0 57.1 Gum (wt. %) 0.6 0.7 0.8 1.4 1.0
Protein in Starch- bran Fraction (%) 3.8 3.3 3.1 3.4 3.2 Protein in
Acid-soluble Protein (%) 88.3 90.8 91.9 94.9 90.6 Protein Recovered
in Acid-soluble Protein (%) 81.6 71.3 67.7 65.9 55.3
______________________________________
TABLE V ______________________________________ Run Number* 18 19 20
21 ______________________________________ Conventional Isolate
(wt.%) 0.8 1.0 1.2 0.8 (total) Acid-soluble Protein (wt.%) A 13.6
13.9 14.7 14.5 B 2.8 3.2 3.0 1.4 C** 0.2 Total 16.4 17.1 17.9 15.9
Starch-bran Fraction (wt.%) 54.0 53.3 53.6 52.2 Gum (wt. %) 2.8 2.0
1.5 1.0 Protein in Starch-bran Fraction (%) 3.4 3.3 3.1 3.8 Protein
in Acid-soluble Protein (%) 84.4 83.8 86.6 91.1 Protein Recovered
in Acid-soluble Protein (%) 62 66 70 66.8
______________________________________ *see Examples VI-IX for
procedure **Acid-soluble protein obtained as a result of third
treatment in Example VIII.
TABLE VI ______________________________________ Run Number 22 23
______________________________________ Conventional Isolate (wt.%)
0.4 Acid-soluble Protein (wt.%) A 8.8 19.4 B 0.1 Total 8.9 19.4
Starch-bran Fraction (wt.%) 73.7* 62.3 Protein in Acid-soluble
Protein (%) 77.8 60.5 Protein Recovered in Acid Protein (%) 28.7
58.7 ______________________________________ *Fraction remaining
after acid extraction.
TABLE VII
__________________________________________________________________________
Solution Separation of Emulsion as a percentage after Protein
Product* pH 0.16 0.25 0.50 1.0 18.0 48.0 hours
__________________________________________________________________________
Acid-soluble Protein 7 27 Acid-soluble Protein 2.6 7 22 22
Acid-soluble Protein** 2.6 0 4 14 24 Conventional Isolate 7 5 26
Insoluble Protein 7 0 Acid-soluble Soybean Protein 7 25 Soybean
Conventional Isolate 7 small
__________________________________________________________________________
*derived from oats unless specified otherwise **Acid-soluble
protein made from oats that were not de-oiled.
* * * * *